// 云函数入口文件
const cloud = require('wx-server-sdk')

cloud.init()


const db = cloud.database();
const col = db.collection('lesson020');
const _ = db.command;

// 云函数入口函数
exports.main = async (event, context) => {
  const wxContext = cloud.getWXContext()

  // 查询数据
  let user = await col.where({
    '_openid':wxContext.OPENID
  }).get();
  user = user.data[0];

  if( user.prize !== null){
    return {
      msg: '你已经抽过奖了!!!',
      success: false
    }
  }

  let rand = Math.random();
  let prize ;
  switch(true){
    case(rand < 0.1):
      prize = 1;
      break;
    case(rand >= 0.1  && rand < 0.4 ):
      prize = 2;
      break;
    case(rand >= 0.4 ):
      prize = 0;
      break;
  }

  // 选中的邮卡数量减一
  let zero = event.selectedArr[0];
  let one = event.selectedArr[1];
  user.words[zero].number -= 1;
  user.words[one].number -= 1;

  await col.where({
    '_openid':wxContext.OPENID
  }).update({
    data:{
      prize: prize,
      words: user.words
    }
  })

  return {
    prize: prize,     
    success: true,
    words: user.words
  }
}